Slide gate and dust cover operator and seal assembly

ABSTRACT

Apparatus for providing a dust free environment in the filling and discharge of bins and other containers is disclosed. The apparatus includes a dual seal which seals directly against a gate assembly. The invention also provides for the introduction of air between inner and outer seals to prevent contaminants from reaching the product. Dust covers are employed on the fill station and discharge station and also on the fill and discharge ends of the bin.

This is a division of application Ser. No. 727,925 filed Jul. 10, 1991,now U.S. Pat. No. 5,095,954 which is a division of application Ser. No.07/476,574, filed Feb. 7, 1990, now U.S. Pat. No. 5,042,538.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to apparatus for providing a dust freeenvironment in the filling and discharge of containers. Moreparticularly, the present invention relates to a slide gate and dustcover operator and seal assembly for use in providing a sealingarrangement for containers of solid materials such as dry powder ortablets.

Previous apparatus for providing a dust free environment for containersis described in the following U.S. Pat. Nos. 3,354,918 to Coleman;3,729,121 to Cannon; 3,985,245 to Schulte; 4,249,679 to Dillman;4,428,504 to Bassett et al.; 4,491,253 to Coleman; and 4,830,233 toThelen et al.

By the present invention, there is provided an improved sealingarrangement which involves a dual seal which seals directly against thegate assembly. In addition, the present invention provides for theintroduction of air between the inner and outer seal to preventcontaminants from reaching the product.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the fill station for the slide gate anddust cover operator and seal assembly of the present invention.

FIG. 2 is a front elevation of the invention as shown in FIG. 1.

FIG. 3 is a side elevation of the invention as shown in FIG. 1.

FIG. 4 is a side elevation in partial cross section showing details ofthe slide gate and dust cover operator and seal assembly of FIG. 1.

FIG. 5 is a cross section taken along line 5--5 of FIG. 4.

FIG. 6 is a cross sectional view of a portion of the discharge stationof the invention.

FIG. 7 is a plan view of the discharge station of the invention.

FIG. 8 is a front elevation of the invention as shown in FIG. 7.

FIG. 9 is a side elevation of the invention as shown in FIG. 7.

FIG. 10 is a perspective view of the discharge station of the invention.

FIG. 11 is a perspective view- of the slide gate and dust cover operatorand seal assembly as employed with the fill station of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the embodiment of the invention as shown in FIGS. 1 through 11, thereis provided a slide gate and dust cover operator and seal assemblyhaving inner and outer seals to prevent contaminants from reaching theproduct.

In FIGS. 1 through 3, there is shown a support frame assembly 18 of thefill station for a container or bin 10, including vertical members 20having a roller conveyor assembly 22 with rollers 24 mounted at thelower end and with right and left guide roller assemblies 26, 28 mountedat the upper end of the frame assembly 18. A fill tube and seal assembly30 is mounted at the top of the frame 18. A slide gate and dust coveroperator assembly 31 is also mounted at the top of the frame 18.

The bin is transferred onto the rollers 24 by an automatically guidedvehicle (AGV) or other type transfer vehicle. The bins employed hereinmay be of stainless steel having a height of about 3 to 8 feet, forexample, and a circular, square or rectangular cross-section having adiameter or width of about 2 to 6 feet, for example. The rollers 26, 28on the side act to guide the bin into position. As shown in FIG. 2,adjustable stops 40 for the bin are provided on the assembly frame, anda proximity sensor 42 is positioned to verify bin position. A dust cover44, of stainless steel or similar material, is located on the fillstation and the cover 44 is in the closed position while the bin isbeing moved into position- in the fill station. In FIG. 4 all componentsare shown in the position as would be the case when the bin is firstpositioned in the fill station of FIG. 1.

In the sequence of steps as carried cut while the bin is in the fillstation, the vacuum 46 is turned on to clean dust from the dust cover44. The dust cover 44 on the fill station is pulled back (to right inFIG. 2) by air cylinder 48 to expose the seals. As shown in FIG. 4, amounting plate 62 supports the filling assembly. A seal retaining flange57 and a gasket 59 along with a mounting flange for the seal assemblyare employed to maintain a sealing environment in conjunction with innerseal 54 and outer seal 56. At the same time, a dust cover 50 on top ofthe bin (FIG. 11) is pulled back to the open position by cylinder 32(FIG. 1). Inner seal 54 is then inflated (see FIGS. 4 and 5). The airsupply 58 to the chamber 60 is turned on and outer seal 56 is theninflated. Seals 54 and 56 are inflated by air passing from an air supplythrough tubes 63 and 65. It is pointed out that the order in which theseals 54, 56 are inflated may be reversed, depending on thecircumstances. Thus if a toxic product is being handled, for example, itis desirable to keep all the product in while in the case of a foodproduct, it is more advantageous to keep contaminants out.

Continuing the sequence of steps, the slide gate 52 is opened by the useof cylinder 64 (FIG. 11). The flow of product into the bin may thencommence, with product flowing through filling tube 30.

After the bin is filled, the cycle is reversed. The outer seal 56 isdeflated, and the positive air supply 58 is turned off. The inner seal54 is then deflated. Seals 54 and 56 are deflated by allowing air topass outwardly through tubes 63 and 65.

As shown in FIG. 11, the fill station located above the bin positionincludes clamps 66 connected to clamp bar 68 for operation by cylinder32 to control opening and closing of the dust cover 50 on the bin. Theopening and closing of the slide gate 52 is controlled by clamps 70connected to clamp bar 72 for operation by cylinder 64. The slide gate52 and dust cover 50 are slidably installed with dust tight seal on thetop opening of the bin.

Tension block assemblies 74 are mounted on plate 82 with operating rods78 extending through the blocks 74 and being operatively engaged withclamps 66.

Tension block assemblies 76 are mounted on plate 82 with operating rods80 extending through the blocks 76 and being operatively engaged withclamps 70.

The tension block assemblies 74, 76 are of conventional constructioncontaining Teflon packings under spring tension to provide properresistance to motion of the rods 78, 80.

With reference to FIG. 11, when the bin is in position, the dust cover50 and slide gate 52 will be positioned in the closed position as shownin FIG. 11 adjacent the bars 68 and 72, respectively. Cylinder 32 isoperated to pull bar 68. Tension blocks 74 hold rods 78 until clamps 66have engaged dust cover 50. At that point, the entire assembly is pulledback by cylinder 32 until dust cover 50 is in the open position, withopening 51 aligned with filling tube 30. It is noted that both dustcover 44 and dust cover 50 operate off the same valve so both will openat the same time. Also the dust cover 44 on the fill station is raisedabove the dust cover 50 on the bin to provide clearance. In a similarmanner, cylinder 64 is operated to pull bar 72. Tension blocks 76 holdrods 80 until clamps 70 have engaged slide gate 52. The assembly ispulled back until slide gate 52 is in the open position with opening 53aligned with opening 51 and filling tube 30. A gasket material 55 isemployed in a strip on each side of the slide gate 52 between the slidegate 52 and the dust cover 50. This gasket material 55 may be mounted onthe valve at the top of the bin. Thus the slide gate 52 may move freelyrelative to the dust cover 50.

In carrying out the closing operation for dust cover 50 and slide gate52, cylinder 64 pushes bar 72 outwardly. Tension blocks 76 hold rods 80,disengaging clamps 70 from the slide gate 52 and bar 72 continues topush the slide gate 52 to the closed position. In a similar manner,cylinder 32 pushes bar 68 outwardly. Tension blocks 74 hold rods 78which disengage clamps 66 from the dust cover 50. Bar 68 continues topush the dust cover 50 to the closed position.

All positions of the components may be verified by position indicatorssuch as proximity switches mounted on the cylinders.

The main purpose of dust cover 44 is to serve as a collection area tocatch residual dust falling from the filling tube. The dust cover 50 onthe bin is closed at all times except during filling. The seals 54, 56can be reinflated when the dust cover is closed to keep the filling tubesealed.

In FIGS. 6 through 10, there is shown the discharge apparatus for use indischarging solid material from the bottom end of the bin. For thisprocedure, the bin will be moved to a discharge station having verticalframe members 90, roller conveyors 91, left 92 and right 93 guiderollers, adjustable stops 94 and a proximity switch 95. Movement of thedust cover 97 is controlled by a cylinder 96 so as to pivot between openand closed positions as shown in FIG. 7. A vibrator 98 on the dischargestation is controlled by an operator to assist in discharging of thebin.

The bin is provided on its exterior bottom surface with a slide gate anddust cover which are the same as the slide gate 52 and dust cover 50 atthe upper end of the bin. The discharge station includes apparatus 100for operating the slide gate and dust cover on the bottom of the binwhich is identical to that shown in FIG. 11 except that it is inverted180 degrees relative to that shown in FIG. 11.

As shown in FIG. 6, the discharge station is provided with inner 110 andouter 112 seals, in the same manner as for the fill station. A sealretaining flange 114 and gasket in combination with a seal assemblymounting flange 116 act to maintain a sealing environment in conjunctionwith inner seal 110 and outer seal 112. An air supply coupling 120provides a source of low pressure air. The discharge tube 122 is mountedin flange 124. A vacuum 126 is provided for use in removing dust. Asupport block 128 is provided for the hinged dust cover and a hinge rod130 is provided for the entire discharge tube assembly 132, with thelatter being shown in FIG. 6 as tipped over for removal or cleaning.

The fill station conveyor 24 and the discharge station conveyor 91 arepowered by a slave drive located on an AGV or transfer type vehicle.Also, both conveyors 24, 91 have an automatically engaged brake whenthis drive is not in operation. The fill and discharge stations may belocated side by side or spaced apart and may be on the same or differentlevels.

The inner and outer seals for the fill and discharge stations are foodgrade inflatable rubber in one embodiment. When these seals areinflated, they extend down and engage the valve assembly on the bin.

By following the filling and discharge procedures as set forth herein,the interior of the bin is never exposed to the atmosphere.

To summarize the operation of the invention at the discharge station, abin is loaded into the discharge station by the use of a poweredconveyor. The vacuum automatically begins and cleans the discharge area.When the bin is in the discharge position, the station dust cover opens.The upper cylinder is extended and the clamps are held in place by meansof a linkage assembly. The cylinder retracts and the clamps close, thusopening the dust cover on the bin. The inner seal and the outer sealwill then inflate. The high volume air begins and the lower cylinderextends and the clamps are held open by means of a second linkageassembly. The cylinder then retracts and the clamps close, thus pullingthe slide gate on the bin open. When the bin is empty, the entireprocedure is reversed. The discharge head assembly swings out of the wayfor easy cleaning.

The features of the present invention include the following:

The dual seal prevents product escape;

The introduction of high volume low pressure air in the cavity betweenthe seals keeps the product in and prevents dust from entering from theoutside;

The vacuum pickup cleans the dust covers automatically;

The dust cover and slide gate are opened and closed mechanically;

The dust cover and slide gate can be operated independently;

The product area is closed to outside contamination;

The discharge head swings out of the way for easy cleaning;

The device has been approved for use in a pharmaceutical operation; and

The entire assembly can be controlled either manually or by a centralcomputer system.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is: 1.Apparatus for providing a dust free environment in the filling ordischarge of solid materials such as dry powder or tablets into or froma bin or other container, comprising:a tubular member for receivingmaterials in the filling or discharge of said solid materials; a planarmember in the form of a seal-retaining flange mounted in fluid tightengagement circumferentially around said tubular member; an inflatableinner seal mounted in said planar member so as to be positionedcircumferentially around said tubular member; an inflatable outer sealmounted in said planar member so as to be positioned circumferentiallyaround said tubular member and radially outwardly of said inner seal,relative to the longitudinal axis of said tubular member; air supplymeans for providing air under pressure to said inner seal; air supplymeans for providing air under pressure to said outer seal, separate fromsaid air supply means for said inner seal; and air supply means forproviding air under pressure between said inner and outer seals.
 2. Amethod for operating apparatus for providing a dust free environment inthe filling or discharge of solid materials such as dry powder ortablets into or from a bin or other container, comprising:(a) providinga tubular member for receiving materials in the filling or discharge ofsaid solid materials; (b) providing a planar member in the form of aseal-retaining flange mounted in fluid tight engagementcircumferentially around said tubular member; (c) providing aninflatable inner seal mounted in said planar member so as to bepositioned circumferentially around said tubular member; (d) providingan inflatable outer seal mounted in said planar member so as to bepositioned circumferentially around said tubular member and radiallyoutwardly of said inner seal, relative to the longitudinal axis of saidtubular member; (e) providing air supply means for supplying air underpressure to said inner seal; (f) providing air supply means forsupplying air under pressure to said outer seal, separate from said airsupply means for said inner seal; and (g) providing air supply means forsupplying air under pressure between said inner and outer seals.